I couldn't find an equivalent expression in English.

Based on the Wikipedia article found by philgoddard, it seems to be the method involving terms that combine current and distance by multiplication.
Searching on "current multiplied by length/distance" and similar phrases brought up "current element" as a candidate, but I believe it means something different.
Likewise I found nothing relevant in English from searches of "current moment" or "moment of current" or "amperometric moment".
A cursory online search of power line sizing/design methods also didn't turn up anything useful for me.

If there isn't an existing common phrase using the word "moments" in English, then I'd suggest a more descriptive expression, along the lines of "products of current and distance" or "current–distance products". (Note the use of an en-dash in the latter, not a hyphen.) Although "moments" can be justified, I would expect it'll be more ambiguous if there is not already an established usage in this specific context.
Given the need to add also "method", I'd opt for the shorter of the above two phrases.

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Note added at 23 hrs (2019-08-21 15:47:53 GMT)
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If the variables have been defined in your text, perhaps you could make it more concise by using mathematical symbols, as in: "the i d method". It's problematic if the symbols aren't already defined in the text. Note the use of italic and the spacing. Note also uppercase "I" might be mistaken for lowercase "l", and uppercase "L" would be read as inductance.